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Point Cloud Segmentation Using Sparse Temporal Local Attention

arXiv.org Artificial Intelligence

However, Point clouds are a key modality used for perception despite a number of successful recent approaches exploiting in autonomous vehicles, providing the means sequential data from 2D video streams for improved for a robust geometric understanding of the surrounding segmentation performance [Hu et al., 2020a; Li et al., 2018; environment. However despite the sensor Paul et al., 2020; Zhu et al., 2019; Jain et al., 2019], there outputs from autonomous vehicles being naturally has been limited exploration into leveraging temporal priors temporal in nature, there is still limited exploration for point cloud segmentation. Existing approaches either calculate of exploiting point cloud sequences for 3D semantic strict correspondences between point features across segmentation. In this paper we propose a novel frames [Cao et al., 2020] or perform global attention [Shi Sparse Temporal Local Attention (STELA) module et al., 2020] between whole point clouds. In the case of the which aggregates intermediate features from a local former, a breakdown of nearest-point matching due to displacement neighbourhood in previous point cloud frames between adjacent point clouds can result in the to provide a rich temporal context to the decoder.


Spatio-Temporal Joint Graph Convolutional Networks for Traffic Forecasting

arXiv.org Artificial Intelligence

Recent studies focus on formulating the traffic forecasting as a spatio-temporal graph modeling problem. They typically construct a static spatial graph at each time step and then connect each node with itself between adjacent time steps to construct the spatio-temporal graph. In such a graph, the correlations between different nodes at different time steps are not explicitly reflected, which may restrict the learning ability of graph neural networks. Meanwhile, those models ignore the dynamic spatio-temporal correlations among nodes as they use the same adjacency matrix at different time steps. To overcome these limitations, we propose a Spatio-Temporal Joint Graph Convolutional Networks (STJGCN) for traffic forecasting over several time steps ahead on a road network. Specifically, we construct both pre-defined and adaptive spatio-temporal joint graphs (STJGs) between any two time steps, which represent comprehensive and dynamic spatio-temporal correlations. We further design dilated causal spatio-temporal joint graph convolution layers on STJG to capture the spatio-temporal dependencies from distinct perspectives with multiple ranges. A multi-range attention mechanism is proposed to aggregate the information of different ranges. Experiments on four public traffic datasets demonstrate that STJGCN is computationally efficient and outperforms 11 state-of-the-art baseline methods.


DeepMind's AI helps untangle the mathematics of knots

#artificialintelligence

Knot theorists proved the validity of a mathematical formula about knots after using machine learning to guess what the formula should be.Credit: DeepMind For the first time, machine learning has spotted mathematical connections that humans had missed. Researchers at AI powerhouse DeepMind, based in London, teamed up with mathematicians to tackle two separate problems -- one in the theory of knots and the other in the study of symmetries. In both cases, AI techniques helped the researchers discover new patterns that could then be investigated using conventional methods. "I was very struck at just how useful the machine-learning tools could be as a guide for intuition," says Marc Lackenby at the University of Oxford, UK, one of the mathematicians who took part in the study. "I was not expecting to have some of my preconceptions turned on their head."


5 ways drones are saving lives and the planet

#artificialintelligence

The overhead buzzing of unmanned aerial vehicles (UAVs) – aka drones – is an increasingly familiar sound in many parts of the world. Whether these helicopter-like devices are flown for fun, military purposes or commercial reasons, the global drone market is predicted to increase annually by nearly 14% between 2020 and 2025. Drones can give operators a birds-eye view of events – including natural disasters – as they unfold. And they can open up difficult-to-access places for emergency supplies to be delivered. This makes them well-suited to help in the response to humanitarian and environmental challenges.


Flexiv Gains World's First CE and ETL Certification for a Force-Controlled Robot

#artificialintelligence

Flexiv, the world leader in general-purpose robotics, has received CE and ETL approval for their Rizon 4 robot, making it the first-ever seven-axis force-controlled adaptive robot to achieve both certifications at the same time. "The CE and ETL certification is an essential regulatory milestone on Flexiv's road to commercialization" Demonstrating the intrinsic safety of the Rizon 4 robot, the CE and ETL approval was awarded by the world's foremost testing, inspection, certification and assurance provider, Intertek. Accepted in the EU and Northern America, the approval enables Flexiv to distribute the Rizon 4 in the European Union, Canada, and the USA. Meeting or exceeding the strict CE and ETL requirements, the Rizon 4 was subjected to hundreds of individual testing, evaluations, and assessments focused on machinery safety, electrical safety, functional safety, environmental reliability, electromagnetic compatibility, and collision detection. During the testing the Rizon 4 was also exposed to temperatures ranging from 0-45 C, dust particulates, and water jets from any direction.


Narrative Cartography with Knowledge Graphs

arXiv.org Artificial Intelligence

Narrative cartography is a discipline which studies the interwoven nature of stories and maps. However, conventional geovisualization techniques of narratives often encounter several prominent challenges, including the data acquisition & integration challenge and the semantic challenge. To tackle these challenges, in this paper, we propose the idea of narrative cartography with knowledge graphs (KGs). Firstly, to tackle the data acquisition & integration challenge, we develop a set of KG-based GeoEnrichment toolboxes to allow users to search and retrieve relevant data from integrated cross-domain knowledge graphs for narrative mapping from within a GISystem. With the help of this tool, the retrieved data from KGs are directly materialized in a GIS format which is ready for spatial analysis and mapping. Two use cases - Magellan's expedition and World War II - are presented to show the effectiveness of this approach. In the meantime, several limitations are identified from this approach, such as data incompleteness, semantic incompatibility, and the semantic challenge in geovisualization. For the later two limitations, we propose a modular ontology for narrative cartography, which formalizes both the map content (Map Content Module) and the geovisualization process (Cartography Module). We demonstrate that, by representing both the map content and the geovisualization process in KGs (an ontology), we can realize both data reusability and map reproducibility for narrative cartography.


Reward-Free Attacks in Multi-Agent Reinforcement Learning

arXiv.org Artificial Intelligence

We investigate how effective an attacker can be when it only learns from its victim's actions, without access to the victim's reward. In this work, we are motivated by the scenario where the attacker wants to behave strategically when the victim's motivations are unknown. We argue that one heuristic approach an attacker can use is to maximize the entropy of the victim's policy. The policy is generally not obfuscated, which implies it may be extracted simply by passively observing the victim. We provide such a strategy in the form of a reward-free exploration algorithm that maximizes the attacker's entropy during the exploration phase, and then maximizes the victim's empirical entropy during the planning phase. In our experiments, the victim agents are subverted through policy entropy maximization, implying an attacker might not need access to the victim's reward to succeed. Hence, reward-free attacks, which are based only on observing behavior, show the feasibility of an attacker to act strategically without knowledge of the victim's motives even if the victim's reward information is protected.


Efficient Symptom Inquiring and Diagnosis via Adaptive Alignment of Reinforcement Learning and Classification

arXiv.org Artificial Intelligence

The medical automatic diagnosis system aims to imitate human doctors in the real diagnostic process. This task is formulated as a sequential decision-making problem with symptom inquiring and disease diagnosis. In recent years, many researchers have used reinforcement learning methods to handle this task. However, most recent works neglected to distinguish the symptom inquiring and disease diagnosing actions and mixed them into one action space. This results in the unsatisfactory performance of reinforcement learning methods on this task. Moreover, there is a lack of a public evaluation dataset that contains various diseases and corresponding information. To address these issues, we first propose a novel method for medical automatic diagnosis with symptom inquiring and disease diagnosing formulated as a reinforcement learning task and a classification task, respectively. We also propose a robust and adaptive method to align the two tasks using distribution entropies as media. Then, we create a new dataset extracted from the MedlinePlus knowledge base. The dataset contains more diseases and more complete symptom information. The simulated patients for experiments are more realistic. Experimental evaluation results show that our method outperforms three recent state-of-the-art methods on different datasets by achieving higher medical diagnosis accuracies with few inquiring turns.


Unsupervised detection and open-set classification of fast-ramped flexibility activation events

arXiv.org Machine Learning

The continuous electrification of the mobility and heating sectors adds much-needed flexibility to the power system. However, flexibility utilization also introduces new challenges to distribution system operators (DSOs), who need mechanisms to supervise flexibility activations and monitor their effect on distribution network operation. Flexibility activations can be broadly categorized to those originating from electricity markets and those initiated by the DSO to avoid constraint violations. Simultaneous electricity market driven flexibility activations may cause voltage quality or temporary overloading issues, and the failure of flexibility activations initiated by the DSO might leave critical grid states unresolved. This work proposes a novel data processing pipeline for automated real-time identification of fast-ramped flexibility activation events. Its practical value is twofold: i) potentially critical flexibility activations originating from electricity markets can be detected by the DSO at an early stage, and ii) successful activation of DSO-requested flexibility can be verified by the operator. In both cases the increased awareness would allow the DSO to take counteractions to avoid potentially critical grid situations. The proposed pipeline combines techniques from unsupervised detection and open-set classification. For both building blocks feasibility is systematically evaluated and proofed on real load and flexibility activation data.


Hindsight Task Relabelling: Experience Replay for Sparse Reward Meta-RL

arXiv.org Artificial Intelligence

Meta-reinforcement learning (meta-RL) has proven to be a successful framework for leveraging experience from prior tasks to rapidly learn new related tasks, however, current meta-RL approaches struggle to learn in sparse reward environments. Although existing meta-RL algorithms can learn strategies for adapting to new sparse reward tasks, the actual adaptation strategies are learned using hand-shaped reward functions, or require simple environments where random exploration is sufficient to encounter sparse reward. In this paper, we present a formulation of hindsight relabeling for meta-RL, which relabels experience during meta-training to enable learning to learn entirely using sparse reward. We demonstrate the effectiveness of our approach on a suite of challenging sparse reward goal-reaching environments that previously required dense reward during meta-training to solve. Our approach solves these environments using the true sparse reward function, with performance comparable to training with a proxy dense reward function.